Grazing winter wheat relieves plant water stress and transiently enhances photosynthesis
Matthew T. Harrison A B C , Walter M. Kelman A , Andrew D. Moore A and John R. Evans BA CSIRO Plant Industry, GPO Box 1600, Canberra, ACT 2601, Australia.
B The Australian National University, Research School of Biology, Canberra, ACT 0200, Australia.
C Corresponding author. Email: matthew.harrison@csiro.au
Functional Plant Biology 37(8) 726-736 https://doi.org/10.1071/FP10040
Submitted: 23 February 2010 Accepted: 19 April 2010 Published: 26 July 2010
Abstract
To model the impact of grazing on the growth of wheat (Triticum aestivum L.), we measured photosynthesis in the field. Grazing may affect photosynthesis as a consequence of changes to leaf water status, nitrogen content per unit leaf area (Na) or photosynthetic enzyme activity. While light-saturated CO2 assimilation rates (Asat) of field-grown wheat were unchanged during grazing, Asat transiently increased by 33–68% compared with ungrazed leaves over a 2- to 4-week period after grazing ended. Grazing reduced leaf mass per unit area, increased stomatal conductance and increased intercellular CO2 concentrations (Ci) by 36–38%, 88–169% and 17–20%, respectively. Grazing did not alter Na. Using a photosynthesis model, we demonstrated that the increase in Asat after grazing required an increase in Rubisco activity of up to 53%, whereas the increase in Ci could only increase Asat by up to 13%. Increased Rubisco activity was associated with a partial alleviation of leaf water stress. We observed a 68% increase in leaf water potential of grazed plants that could be attributed to reduced leaf area index and canopy evaporative demand, as well as to increased rainfall infiltration into soil. The grazing of rain-fed grain cereals may be tailored to relieve plant water stress and enhance leaf photosynthesis.
Additional keywords: defoliation, herbivory, leaf mass per unit area, Rubisco, specific leaf area, transpiration.
Acknowledgements
We appreciate the assistance of Stephanie McCaffery for nitrogen analyses, Phillip Dunbar for site management and Bruce Isaac for sheep management. We are grateful to Hugh Dove, Mark Smith and Scott McDonald for help with field sampling. Thanks also to the Grains Research and Development Corporation and the Australian Government for financial support of this work.
Anderson TM,
Dong Y, McNaughton SJ
(2006) Nutrient acquisition and physiological responses of dominant Serengeti grasses to variation in soil texture and grazing. Journal of Ecology 94, 1164–1175.
| Crossref | GoogleScholarGoogle Scholar |
CAS |
Anten NPR, Ackerly DD
(2001) Canopy-level photosynthetic compensation after defoliation in a tropical understorey palm. Functional Ecology 15, 252–262.
| Crossref | GoogleScholarGoogle Scholar |
Bortolini PC,
de Moraes A, Carvalho PCD
(2005) Forage and grain yield of white oat under grazing. Revista Brasileira De Zootecnia – Brazilian Journal of Animal Science 34, 2192–2199.
Caldwell MM,
Richards JH,
Johnson DA,
Nowak RS, Dzurec RS
(1981) Coping with herbivory – photosynthetic capacity and resource allocation in two semi-arid Agropyron bunchgrasses. Oecologia 50, 14–24.
| Crossref | GoogleScholarGoogle Scholar |
Cataldo DA,
Haroon M,
Schrader LE, Youngs VL
(1975) Rapid colorimetric determination of nitrate in plant tissue by nitration of salicylic acid. Communications in Soil Science and Plant Analysis 6, 71–80.
| Crossref | GoogleScholarGoogle Scholar |
CAS |
Doescher PS,
Svejcar TJ, Jaindl RG
(1997) Gas exchange of Idaho fescue in response to defoliation and grazing history. Journal of Range Management 50, 285–289.
| Crossref | GoogleScholarGoogle Scholar |
Evans JR
(1989) Photosynthesis and nitrogen relationships in leaves of C3 plants. Oecologia 78, 9–19.
| Crossref | GoogleScholarGoogle Scholar |
Fahnestock JT, Detling JK
(2000) Morphological and physiological responses of perennial grasses to long-term grazing in the Pryor Mountains, Montana. American Midland Naturalist 143, 312–320.
| Crossref | GoogleScholarGoogle Scholar |
Fay PA,
Hartnett DC, Knapp AK
(1993) Increased photosynthesis and water potentials in Silphium integrifolium galled by cynipid wasps. Oecologia 93, 114–120.
Flexas J,
Baron M,
Bota J,
Ducruet JM, Galle A ,
et al
.
(2009) Photosynthesis limitations during water stress acclimation and recovery in the drought-adapted Vitis hybrid Richter-110 (V. berlandieri × V. rupestris). Journal of Experimental Botany 60, 2361–2377.
| Crossref | GoogleScholarGoogle Scholar |
CAS |
PubMed |
Hamilton EW, Frank DA
(2001) Can plants stimulate soil microbes and their own nutrient supply? Evidence from a grazing tolerant grass. Ecology 82, 2397–2402.
| Crossref | GoogleScholarGoogle Scholar |
Kelly KB,
Stockdale CR, Mason WK
(2005) The productivity of irrigated legumes in northern Victoria. 2. Effect of grazing management. Australian Journal of Experimental Agriculture 45, 1577–1585.
| Crossref | GoogleScholarGoogle Scholar |
Kelman WM, Dove H
(2009) Growth and phenology of winter wheat and oats in a dual-purpose management system. Crop and Pasture Science 60, 921–932.
| Crossref | GoogleScholarGoogle Scholar |
Lavigne MB,
Little CHA, Major JE
(2001) Increasing the sink : source balance enhances photosynthetic rate of 1-year-old balsam fir foliage by increasing allocation of mineral nutrients. Tree Physiology 21, 417–426.
|
CAS |
PubMed |
Layne DR, Flore JA
(1995) End product inhibition of photosynthesis in Prunus cerasus L. in response to whole plant source–sink manipulation. Journal of the American Society for Horticultural Science 120, 583–599.
Little CHA,
Lavigne MB, Ostaff DP
(2003) Impact of old foliage removal, simulating defoliation by the balsam fir sawfly, on balsam fir tree growth and photosynthesis of current-year shoots. Forest Ecology and Management 186, 261–269.
| Crossref | GoogleScholarGoogle Scholar |
Meyer GA
(1998) Pattern of defoliation and its effect on photosynthesis and growth of goldenrod. Functional Ecology 12, 270–279.
| Crossref | GoogleScholarGoogle Scholar |
Morgan JM
(1980) Osmotic adjustment in the spikelets and leaves of wheat. Journal of Experimental Botany 31, 655–665.
| Crossref | GoogleScholarGoogle Scholar |
Morrison KD, Reekie EG
(1995) Pattern of defoliation and its effect on photosynthetic capacity in Oenothera biennis. Journal of Ecology 83, 759–767.
| Crossref | GoogleScholarGoogle Scholar |
Nowak RS, Caldwell MM
(1984) A test of compensatory photosynthesis in the field – implications for herbivory tolerance. Oecologia 61, 311–318.
| Crossref | GoogleScholarGoogle Scholar |
Oleksyn J,
Karolewski P,
Giertych MJ,
Zytkowiak R,
Reich PB, Tjoelker MG
(1998) Primary and secondary host plants differ in leaf-level photosynthetic response to herbivory: evidence from Alnus and Betula grazed by the alder beetle, Agelastica alni. New Phytologist 140, 239–249.
| Crossref | GoogleScholarGoogle Scholar |
Pinkard EA,
Battaglia M, Mohammed CL
(2007) Defoliation and nitrogen effects on photosynthesis and growth of Eucalyptus globulus. Tree Physiology 27, 1053–1063.
|
CAS |
PubMed |
Pinkard EA,
Beadle CL,
Davidson NJ, Battaglia M
(1998) Photosynthetic responses of Eucalyptus nitens (Deane and Maiden) maiden to green pruning. Trees – Structure and Function 12, 119–129.
Shimada S,
Kokubun M,
Shibata H, Matsui S
(1992) Effect of water supply and defoliation on photosynthesis, transpiration and yield of soybean. Nihon Sakumotsu Gakkai Kiji 61, 264–270.
Teixeira EI,
Moot DJ, Brown HE
(2008) Defoliation frequency and season affected radiation use efficiency and dry matter partitioning to roots of lucerne (Medicago sativa L.) crops. European Journal of Agronomy 28, 103–111.
| Crossref | GoogleScholarGoogle Scholar |
CAS |
Toft NL,
McNaughton SJ, Georgiadis NJ
(1987) Effects of water stress and simulated grazing on leaf elongation and water relations of an east-African grass, Eustachys paspaloides. Australian Journal of Plant Physiology 14, 211–226.
| Crossref | GoogleScholarGoogle Scholar |
Turnbull TL,
Adams MA, Warren CR
(2007) Increased photosynthesis following partial defoliation of field-grown Eucalyptus globulus seedlings is not caused by increased leaf nitrogen. Tree Physiology 27, 1481–1492.
|
CAS |
PubMed |
Virgona JM,
Gummer FAJ, Angus JF
(2006) Effects of grazing on wheat growth, yield, development, water use, and nitrogen use. Australian Journal of Agricultural Research 57, 1307–1319.
| Crossref | GoogleScholarGoogle Scholar |
von Caemmerer S, Farquhar GD
(1981) Some relationships between the biochemistry of photosynthesis and the gas exchange of leaves. Planta 153, 376–387.
| Crossref | GoogleScholarGoogle Scholar |
CAS |
von Caemmerer S, Farquhar GD
(1984) Effects of partial defoliation, changes of irradiance during growth, short-term water stress and growth at enhanced p(CO2) on the photosynthetic capacity of leaves of Phaseolus vulgaris L. Planta 160, 320–329.
| Crossref | GoogleScholarGoogle Scholar |
CAS |
von Caemmerer S,
Evans JR,
Hudson GS, Andrews TJ
(1994) The kinetics of ribulose-1,5-bisphosphate carboxylase/oxygenase in-vivo inferred from measurements of photosynthesis in leaves of transgenic tobacco. Planta 195, 88–97.
|
CAS |
Wareing PF,
Khalifa MM, Treharne KJ
(1968) Rate limiting processes in photosynthesis at saturating light intensities. Nature 220, 453–457.
| Crossref | GoogleScholarGoogle Scholar |
CAS |
PubMed |
Winter SR, Thompson EK
(1987) Grazing duration effects on wheat growth and grain yield. Agronomy Journal 79, 110–114.
Yang Z, Midmore DJ
(2004) Experimental assessment of the impact of defoliation on growth and production of water-stressed maize and cotton plants. Experimental Agriculture 40, 189–199.
| Crossref | GoogleScholarGoogle Scholar |
Zadoks JC,
Chang TT, Konzak CF
(1974) Decimal code for growth stages of cereals. Weed Research 14, 415–421.
| Crossref | GoogleScholarGoogle Scholar |
Zhao W,
Chen SP,
Han XG, Lin GH
(2009) Effects of long-term grazing on the morphological and functional traits of Leymus chinensis in the semiarid grassland of Inner Mongolia, China. Ecological Research 24, 99–108.
| Crossref | GoogleScholarGoogle Scholar |
Zhou R, Quebedeaux B
(2003) Changes in photosynthesis and carbohydrate metabolism in mature apple leaves in response to whole plant source–sink manipulation. Journal of the American Society for Horticultural Science 128, 113–119.
|
CAS |
